The object of the present invention is new detergent-dispersant additives based on sulfurized and superalkalinized alkylphenates of alkaline-earth metals and alkylsalicylates of alkali metals for lubricating oils. The Applicant has described related additives in his French patent application 85/13731 published as U.S. Pat. No. 2,587,353 on Mar. 20, 1987.
It is known (U.S. Pat. No. 3,410,798 and U.S. Pat. No. 3,595,791) how to prepare detergent additives by carboxylation of a potassium alkylphenate, exchange with calcium chloride, then sulfurization of the mixture of alkylphenate and alkylsalicylate of calcium with sulfur in the presence of lime, a carboxylic acid, an alkylene glycol or alkyl ether of alkylene glycol.
The product thus obtained consists mainly of a mixture of sulfurized calcium alkylphenate and partially sulfurized calcium alkylsalicylate. The Applicant has noted that if salts of alkali metals are present in this type of product, its performance is improved.
These products that are the object of the invention are characterized in that they are obtained by carrying out the following stages:
a. In a first stage the neutralization of an alkylphenol carrying one or more C.sub.8 -C.sub.30, preferably C.sub.12 -C.sub.30, alkyl substituents by means of an alkali metal hydroxide optionally in the presence of a azeotropic solvent forming an azeotrope with the reaction water selected among the aromatic or aliphatic hydrocarbons with a boiling point above 70.degree. C., said neutralization operation being carried out at a temperature at least equal to that of the formation of the azeotrope or at a temperature greater than 200.degree. C. in the absence of an azeotropic solvent, the quantities of reagents used corresponding to the molar ratio:
Alkali metal hydroxide/alkylphenol ranging from 0.1 to 1 and preferably from 0.1 to 0.5; PA1 Elimination of the water and, optionally, any azeotropic solvent to form a first product; PA1 Sulfur/initial alkylphenol ranging from 0.7 to 1.5, preferably from 0.7 to 1.3, PA1 Alkaline-earth base/initial alkylphenol from 0.5 to 2, preferably on the order of 0.8 to 1.7, PA1 Alkaline-earth base/alkylene glycol ranging from 1.2 to 1.4, PA1 sulfurization of the product obtained by carboxylation, by means of elemental sulfur possibly in the presence of an alkali metal hydroxide, according to a quantity corresponding to an initial alkali metal hydroxide/alkylphenol molar ratio of 1/50 to 1/30 (especially when all the alkali metal alkylphenate has been converted into alkali metal alkylsalicylate) at a temperature on the order of 140.degree. to 200.degree. C., preferably on the order of 160.degree. to 175.degree. C., the sulfur/initial alkylphenol molar ratio ranging from 0.7 to 1.5, preferably from 0.7 to 1.3; this operation generally lasts from 2 to 6 hours; PA1 the addition at a temperature of 50.degree. to 80.degree. C. of an alkaline earth base, an alkylene glycol and an azeotropic solvent selected among the aromatic hydrocarbons, the aliphatic hydrocarbons, and the monoalcohols with a boiling point above 120.degree. C., and preferably above 150.degree. C., the quantities of reagents corresponding to the following molar ratios:
b. In a second stage, the carboxylation of said first product to convert the alkali metal alkylphenate formed in said first product into an alkali metal alkylsalicylate by means of carbon dioxide at a temperature from 100.degree. to 185.degree. C. (preferably 140.degree.-185.degree. C.) under a pressure which can range from atmospheric pressure to 15 bars (preferably on the order of 5 bars) for at least 1 hour in the presence of a dilution oil or an aromatic or aliphatic hydrocarbon with a boiling point higher than 70.degree. C., the quantity of CO.sub.2 corresponding to that necessary to obtain a maximum conversion of the initial alkylphenol into alkali metal alkylsalicylate, to form a second product;
c. In a third stage, the sulfurization-superalkalinization of a mixture of said second product formed by adding elemental sulfur in the presence of an alkaline-earth base, an alkylene glycol and an azeotropic solvent chosen among the aromatic hydrocarbons, aliphatic hydrocarbons and monoalcohols with a boiling point greater than 120.degree. C. and preferably greater than 150.degree. C., at a temperature on the order of 140.degree. to 240.degree. C., the quantities of reagents used corresponding to the following molar ratios:
followed by carbonation of the said mixture with carbon dioxide at a temperature of 100.degree.-185.degree. C. and under a pressure close to atmospheric pressure, the quantity of CO.sub.2 used lying between that which can be completely absorbed by the reaction medium and an excess of 30% of this quantity,
d. Elimination of the alkylene glycol and the azeotropic solvent after addition of dilution oil,
e. Filtration to eliminate the sediments.
Among the alkali metal hydroxides that can be used in the neutralization stage, one may cite soda, potash, lithium hydroxide.
Among the azeotropic aromatic or aliphatic solvents, one may cite xylene, toluene, cyclohexane.
Among the monoalcohols with a boiling point greater than 120.degree. C. one, may cite 2-ethylhexanol, the oxoalcohols, decyl alcohol, tridecyl alcohol, 2-butoxyethanol, 2-butoxypropanol, methylether of propylene glycol.
Among the alkylene glycols, one may cite: ethylene glycol, diethylene glycol.
Among the alkaline earth bases that can be used, one may cite the oxides or hydroxides of calcium, barium or strontium and especially calcium.
Among the dilution oils that can be used, one may cite preferably the paraffin oils such as the 100 Neutral oil; the naphthenic or mixed oils may also be suitable.
The first stage, that is, the neutralization stage, is advantageously carried out at a pressure close to atmospheric pressure.
When this neutralization process is carried out without an azeotropic solvent, it is generally carried out at a temperature on the order of 250.degree. C.; when 2-ethylhexanol is used as an azeotropic solvent, a temperature on the order of 160.degree.-170.degree. C. is preferred; when the azeotropic solvent is cyclohexane, a temperature of 70.degree.-80.degree. C. is quite suitable.
The quantity of any azeotropic solvent used in this stage corresponds to that necessary to obtain a fluid medium, that is, of a viscosity below approximately 30.times.10.sup.-6 m.sup.2 /s under the reaction conditions.
The second stage, the carboxylation stage, can be carried out in the presence or in the absence of an azeotropic solvent possibly used in the neutralization stage.
The quantity of CO.sub.2 to be introduced corresponds to that necessary to obtain a maximum conversion of the initial alkylphenol into alkali metal alkylsalicylate. This maximum conversion is a function of the alkali metal/alkylphenol molar ratio; when this ratio is 1, the maximum conversion is on the order of 85%; when the ratio is 0.5, it is approximately 45%.
This carboxylation operation generally lasts from 1 to 6 hours.
If the medium is viscous (viscosity greater than 200.times.10.sup.-6 m.sup.2 /s at 100.degree. C.), which is the case especially when the alkaline hydroxide used is lithium hydroxide, an azeotropic solvent of the type used in the sulfurization-superalkalinization stage can be added at the end of the carboxylation.
The third stage, the sulfurization-superalkalinization stage, is preferably carried out at a temperature on the order of 140.degree. to 160.degree. C. for approximately 3-6 hours.
This operation may possibly be carried out in the presence of an additional quantity of alkylphenol when the conversion of the alkylphenol into alkali metal alkylsalicylate is high (at least 40%) so as to bring this conversion to a value on the order of 15 to less than 40%, generally in the order of 20 to 30%.
The carbonation itself is advantageously carried out at a temperature of 145.degree.-180.degree. C. under a pressure of approximately 930.times.10.sup.2 to 1010.times.10.sup.2 Pa.
According to one embodiment, the sulfurization-superalkalinization operation can be carried out by
alkaline earth base/initial alkylphenol of 0.5 to 2, preferably on the order of 0.8 to 1.7; PA2 alkaline earth base/alkylene glycol on the order of 1.2 to 1.4; PA2 then carbonation as indicated above.
After carbonation, dilution oil is introduced in a quantity such that the quantity of oil contained in the final product represents from 25 to 65 wt % of said product and preferably from 30 to 50 wt % of said product.
The additives that are the object of the invention exhibit high basicity; the TBN (total base number) of the additives based on calcium salts, for example, easily reaches 250 to 300 or more.
The quantity of additive to be used to improve the detergent-dispersant properties of lubricating oils is a function of the future use of said oils.
Thus for an oil for gasoline motors, the quantity of additive to be added generally lies between 1 and 3 wt %; for an oil for a diesel motor, it generally lies between 1.5 and 5 wt %; for an oil for a marine motor, it generally lies between 10 and 30%.
The lubricating oils that can thus be improved can be selected among very varied lubricating oils, such as lubricating oils with a naphthene base, with a paraffin base and with a mixed base, from other hydrocarbon lubricants, for example, lubricating oils derived from oil products, and synthetic oils, for example, alkaline polymers, polymers of the alkylene oxide type and their derivatives, including polymers of alkylene oxide prepared by polymerizing alkylene oxide in the presence of water or alcohols, for example, ethyl alcohol, the esters of dicarboxylic acids, liquid esters of acids of phosphorus, alkylbenzenes and dialkylbenzenes, polyphenyls, alkyl biphenyl ethers, polymers of silicon.
Additional additives can also be present in said lubricating oils besides detergent-dispersant additives obtained according to the process of the invention; one may cite, for example, antioxidant and anticorrosion additives and ashless dispersant additives.